n = int(input())
lst = list(input())
r = lst.count('R')

count = 0

for i in range(0, r):
  if lst[i] == 'R':
    count += 1
    
print(r-count) n = int(input()) n int(input()) int input() input lst = list(input()) lst list(input()) list input() input r = lst.count('R') r lst.count('R') lst.count lst count 'R' count = 0 count 0 for i in range(0, r):
  if lst[i] == 'R':
    count += 1
     i range(0, r) range 0 r if lst[i] == 'R':
    count += 1
     lst[i] == 'R' lst[i] lst i 'R' count += 1 count 1 print(r-count) print r-count r count count += 1 1 count r = lst.count('R') lst.count('R') r count = 0 0 count lst = list(input()) list(input()) lst n = int(input()) int(input()) n
n = int(input())
lst = list(input())
r = lst.count('R')

count = 0

for i in range(0, r):
  if lst[i] == 'R':
    count += 1
    
print(r-count)